Contact: Aristide Lemaître
"Classical" electronics uses electron charge to transport information. However these carriers also possess an intrinsic property as their charge and mass, the spin. "Spin" electronics (or spintronics) is based on this additional degree of freedom. This novel field opens a wide range of applications (magnetic memories, sensors…) and physical studies (spin coherence, magnetic properties…).
To manipulate the carrier spin, we use semimagnetic semiconductors. These materials are semiconductors (e.g. GaAs, CdTe) for which a part of the cations have been replaced by a transition element (Mn, Fe…). Their originality relies on the coupling between the delocalized electrons from the valence and conduction bands and the localized magnetic moments. This exchange interaction is responsible for the large magnetic properties of these compounds (spin splitting of the conduction and valence bands, spin polarisation of carriers, ferromagnetic and paramagnetic phases, giant magnetoptical effects…)
At C2N we focus our activity on the compound (Ga,Mn)As, which exhibits a ferromagnetic phase with a rather high Curie temperature, up to 170 K. In this material the origin of the ferromagnetism is now well established and arises from the coupling of the Mn magnetic moments to the delocalized (holes) carriers.
Figure: Magnetic domains measured by Kerr microscopy of a thin (Ga,Mn)(As,P) layer
Topological insulators are bulk insulators with topologically protected edge states. They exist in 1D, 2D, and 3D. In the ELPHYSE group we investigate the growth of thin films of 3D topological insulator Bi1-xSbx by molecular beam epitaxy. The figure shows a cut of the band structure obtained by Angular Resolved PhotoEmission Spectrocopy at beamline Cassiopée at synchrotron SOLEIL. The sample consists of 15 nm thick Bi0.85Sb0.15 layer deposited on a 111 Si substrate.
Figure: Band structure of a thin Bi0.85Sb0.15 layer obtained by ARPES at SOLEIL (Cassiopée)
We are also involved with the GOSS group in investigating topological edge states with photons (J. Bloch's and S. Ravet's group) and phonons (D. Kimura's group). The III-V heterostructures are grown by our team.
Publications (since 2018)
Topological surface states in ultrathin Bi1−xSbx layers, L. Baringthon, Thi Huong Dang, H. Jaffrès, N. Reyren, J.-M. George, M. Morassi, G. Patriarche, A. Lemaître, F. Bertran, and P. Le Fèvre, Phys. Rev. Materials 6, 074204 (2022)
- Topological surface states in epitaxial (SnBi2Te4)n(Bi2Te3)m natural van der Waals superlattices, S. Fragkos, L. Baringthon, P. Tsipas, E. Xenogiannopoulou, P. Le Fèvre, P. Kumar, H. Okuno, N. Reyren, A. Lemaitre, G. Patriarche, J.-M. George, and A. Dimoulas, Phys. Rev. Materials 5, 014203 (2021)
- Spin–orbit torque switching of a ferromagnet with picosecond electrical pulses, K. Jhuria, J. Hohlfeld, A. Pattabi, E. Martin, A. Y. Arriola Córdova, X. Shi, R. Lo Conte, S. Petit-Watelot, J.-C. Rojas-Sanchez, G. Malinowski, S. Mangin, A. Lemaître, M. Hehn, J. Bokor, R. B. Wilson & J. Gorchon, Nature Electronics 3, 680 (2020)
- Time- and space-resolved nonlinear magnetoacoustic dynamics, M. Kraimia, P. Kuszewski, J.-Y. Duquesne, A. Lemaître, F. Margaillan, C. Gourdon, and L. Thevenard, Phys. Rev. B 101, 144425 (2020)
- Exploring the shear strain contribution to the uniaxial magnetic anisotropy of (Ga,Mn)As, M. Kraimia, L. Largeau, K. Boujdaria, B. Croset, C. Mocuta, A. Lemaître, C. Gourdon, and L. Thevenard, J. Appl. Phys. 127, 093901 (2020)
- Common universal behavior of magnetic domain walls driven by spin-polarized electrical current and magnetic field, R. Díaz Pardo, N. Moisan, L. J. Albornoz, A. Lemaître, J. Curiale, and V. Jeudy, Phys. Rev. B 100, 184420 (2019)
- Universal dimensional crossover of domain wall dynamics in ferromagnetic films, W. Savero Torres, R. Díaz Pardo, S. Bustingorry, A. B. Kolton, A. Lemaître, and V. Jeudy, Phys. Rev. B 99, 201201(R) (2019)
- Field-Free Magnetization Switching by an Acoustic Wave, I.S. Camara, J.-Y. Duquesne, A. Lemaître, C. Gourdon, and L. Thevenard, Phys. Rev. Applied 11, 014045 (2019)
- Magneto-optical Kerr spectroscopy in ferromagnetic semiconductors: determination of the intrinsic complex magneto-optical Voigt constant, H Riahi, M A Maaref, A Lemaître and Kui-juan Jin, Semicond. Sci. Technol. 33, 125015 (2019)
- Angular-resolved photoemission electron spectroscopy and transport studies of the elemental topological insulator α-Sn, Q. Barbedienne, J. Varignon, N. Reyren, A. Marty, C. Vergnaud, M. Jamet, C. Gomez-Carbonell, A. Lemaître, P. Le Fèvre, F. Bertran, A. Taleb-Ibrahimi, H. Jaffrès, J.-M. George, and A. Fert, Phys. Rev. B 98, 195445 (2018)
- Resonant magneto-acoustic switching: influence of Rayleigh wave frequency and wavevector, P. Kuszewski, I. S. Camara, N. Biarrotte, L. Becerra, J. von Bardeleben, W. Savero Torres, A. Lemaître, C. Gourdon, J.-Y. Duquesne and L. Thevenard, J. Phys.: Condens. Matter 30, 244003 (2018)